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建立了一个基于计算流体力学(CFD)/FW-H(Ffowcs Williams-Hawkings)方程的预测剪刀式尾桨悬停状态气动性能和噪声特性的分析方法。该方法首先采用CFD方法对尾桨流场进行求解,并应用嵌套网格技术对流场空间进行离散。控制方程采用非惯性坐标系下的Navier-Stokes方程,空间方向采用二阶迎风格式(Roe格式)进行求解,时间方向采用隐式LU-SGS(Lower-Upper Symmetric Gauss-Seidel)格式进行推进。在此基础上,采用FW-H方程将尾桨噪声声压扰动传播至远场,以获得尾桨的噪声特性。应用该方法对两种剪刀式尾桨构型(“L”构型和“U”构型)进行了计算研究,对比分析了剪刀式尾桨在气动力和噪声方面与常规尾桨的差别,以及两个重要构型参数(剪刀角和轴向间距)对剪刀式尾桨气动力和噪声的影响规律。计算结果表明,构型参数对剪刀式尾桨气动力和噪声特性影响很大,合理地选择构型参数可以降低尾桨噪声水平。
A method to predict the aerodynamic performance and noise characteristics of scissor-type tail rotor hovering states based on CFD / FW-H (Ffowcs Williams-Hawkings) equations was established. In this method, CFD method is used to solve the tail rotor flow field and the nested grid technique is used to disperse the flow field space. The governing equations are Navier-Stokes equations in a non-inertial coordinate system. The spatial directions are solved by the second-order upwind scheme (Roe scheme), and the time-domain scheme is augmented by an implicit LU-SGS (Lower-Upper Symmetric Gauss-Seidel) scheme. On this basis, the FW-H equation is used to propagate the sound pressure disturbance of the tail rotor noise to the far field to obtain the noise characteristics of the tail rotor. In this paper, two scissor-type tail rotor configurations (“L” configuration and “U” configuration) are calculated and compared with those of the conventional tail The difference of paddles and the influence of two important configuration parameters (scissor angle and axial distance) on the aerodynamic force and noise of scissor-type tail rotor. The results show that the configuration parameters greatly influence the aerodynamic and noise characteristics of the scissor-type tail rotor, and reasonable configuration parameters can reduce the noise level of the tail rotor.